Many tissue products, such as toilet paper and paper towels, are typically formed into large supply rolls after being manufactured. After the supply rolls are formed, the rolls are rewound into smaller sized rolls, which are generally more useful for commercial purposes. For example, in many conventional processes, the tissue is wound onto a hollow cylindrical core made of paper stock during a winding and converting operation.
Once formed into smaller rolls, the rolls of material are typically fed to a packaging line and wrapped in groups such as by being encased in a plastic film. The wrapped groups are then placed in boxes and shipped to customers.
Current wrapping machines are of two primary styles, reciprocating single sheet feeding wrappers and continuous flow wrappers. Reciprocating wrappers cut individual sheets of plastic film, feed the film into a machine, and push the product through the sheet to cover three sides of the product. The package is first sealed into a tube and the sides of the package are then sealed by heated belts. Reciprocating wrappers are capable of automatically adjusting to rolled products that may vary in size and in firmness because it is the contents of the package that determine the tightness of the wrap. Reciprocating wrappers, however, are prone to mechanical wear from the constant traversing load that is placed on key components and because of the reciprocating motion, generally run at lower operating speeds.
Continuous motion wrappers, on the other hand, may include an in-feed conveyor and a sorter for placing the rolls of material into groups of a desired size. The groups are then fed to a forming shoulder where the groups are placed in a tube formed from a plastic packaging film. The forming shoulder is configured to change a flat sheet of continuous film into a continuous tube sized to the product. The forming shoulder, however, is typically sized for only one combination of roll diameter and firmness. Products that have a lower firmness value may result in a loose pack while products that have high firmness values can cause machine jam-ups. Continuous flow wrappers, in comparison to reciprocating wrappers, are mechanically simpler, are less prone to wear, and, in some embodiments, may run at higher speeds. More recently, continuous flow wrappers that can handle more than one layer of product has further increased their versatility. One embodiment of a continuous motion wrapper, for example, is described in U.S. Pat. No. 5,195,300, which is incorporated herein by reference.
In view of the above, however, a need remains for an improved wrapping apparatus that combines the advantages of reciprocating wrappers with the advantages of continuous motion wrappers. Specifically, a need exists for a wrapping apparatus capable of operating at high speeds that is mechanically simple and does not place a tremendous amount of stress on the packaging material as the material is wrapped around the product and does not require a fixed forming shoulder to form the wrapping material around the package. Also, an added advantage is a wrapper with these features that permits the use of recycled, low caliper wrapping material or paper as the wrapping medium.